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1. an erythrocyte with a dark center surrounded by a light band that again is encircled by a darker ring; it thus resembles a shooting target; such cells appear in target-cell anemias or after splenectomy; Synonym(s): Mexican hat cell
2. a cell lysed by cytotoxic T lymphocytes, as in graft rejection.
1. A cell selectively affected by a particular agent, such as a virus, drug, or hormone.
2. An abnormal red blood cell having a dark center surrounded by a light band that is itself encircled by a darker ring, seen in certain anemias and after splenectomy.
Endocrinology A functional term referring to a cell (target cell) which responds to a hormone, factor or other substance
Haematology Codocyte, Mexican hat cell A term referring to the morphology of red cells which have an increased surface membrane to volume ratio and often an increased diameter. Target cells are characterised by a central haemoglobin-richer (relative to membrane) area surrounded by an area of pallor, which in turn is surrounded by a peripheral haemoglobin-richer zone. Target cells may be seen after splenectomy or acute blood loss, in liver disease and in iron deficiency; in these conditions, the MCV may be normal or increased. Target cells can also be associated with a relative decrease in haemoglobin—HbC, HbS—sickle cell anaemia, thalassaemia or combinations of haemoglobin diseases. Target cells are seen when there is a relative increase in the membrane itself as occurs in LCAT (lecithin-cholesterol acyl transferase) deficiency or in obstructive jaundice. Finally, target cells may be mere artifacts due to slow drying of smears in a humid environment or occur in smears made from specimens anticoagulated with excessive EDTA. Drying artifact is suggested by the presence of numerous target cells in some fields, but not in other fields
Target cells associated with HbC may have slightly reduced or normal MCV, whereas those associated with HbE disorders or HbH disease exhibit a varying degree of microcytosis
Immunology A functional term for MHC class I ‘restricted’ self cells which have undergone a viral, tumour-related or other transformation and present antigens to cytotoxic T cells
Pathology The finding in cells of intracytoplasmic—targetoid—vacuoles is suggestive of lobular carcinoma in situ; 2/3 of cells contain mucin
tar·get cell(tahr'gĕt sel)
1. An erythrocyte in target cell anemia, with a dark center surrounded by a light band that again is encircled by a darker ring, thus resembling a target used in practice with firearms or archery; such cells also appear after splenectomy.
1. . An erythrocyte with a dark rounded central area surrounded by a lightly stained clear ring, which in turn is surrounded by a dense ring of peripheral cytoplasm. It is present in certain blood disorders, such as thalassemia, and in patients who have no spleen. See: hemoglobin C disease for illus Synonym: codocyte; leptocyte
2. . The cell at which a signal (e.g., hormone or nerve impulse) is aimed.illustration
See also: cell